A rock fragment, in sedimentary geology, is a sand-sized particle or sand grain that is made up of multiple grains that are connected on the grain scale. These can include grains which are sand-sized themselves (a

granitic A granitoid is a generic term for a diverse category of coarse-grained igneous rocks that consist predominantly of quartz, plagioclase, and alkali feldspar. Granitoids range from plagioclase-rich tonalites to alkali-rich syenites and from quartz- ...

rock fragment), or finer-grained materials ( shale fragments). This definition is used for QFR ternary diagrams, provenance analysis, and in the

Folk classification The Folk classification, in geology, is a technical descriptive classification of sedimentary rocks devised by Robert L. Folk, an influential sedimentary petrologist and Professor Emeritus at the University of Texas. Folk's sandstone (clastic) c ...

scheme, mainly in sandstones.

References

*Folk, R.L., 1974, Petrology of Sedimentary Rocks: Austin, TX, Hemphill Press, second edition, 182 p. Petrology {{petrology-stub